K 10
svn:author
V 6
scottl
K 8
svn:date
V 27
2012-08-31T10:07:38.115179Z
K 7
svn:log
V 609
Heavily optimize the case of small RX packets of 160 bytes or less.  For
this case, allocate a plain mbuf and copy the frame into it, then send the
copy up the stack, leaving the original mbuf+cluster in place in the
receive ring for immediate re-use.  This saves a trip through 2 of the
3 zones of the compound mbuf allocator, a trip through busdma, and a trip
through the 1 of the 3 mbuf destructors.  For our load at Netflix, this can
lower CPU consumption by as much as 20%.  The copy algorithm is based on
investigative work from Luigi Rizzo earlier in the year.

Reviewed by:	jfv
Obtained from:	Netflix

END